The Creosoted Wood Block: One Step in the Evolution of St. Louis Paving

| by Ryan J. Reed,

On a recent walk through downtown St. Louis I came upon a historic remnant of the city's struggle to cope with the problematic street system during the late nineteenth century. On the west side of 10th Street, a portion of asphalt had failed in the alley bisecting the block between Olive and Locust Streets. The broken asphalt revealed a tightly laid bed of creosoted wood block pavers. City officials and engineers had attempted to find a durable and inexpensive paving material to contend with fluctuations in weather coupled with the heavy vehicular traffic of a growing city. These few historic pavers represent St. Louis' nearly century-long experiment with wood block.

During the nineteenth century, St. Louis streets were largely unpaved. The city's limited funds could not support the ever-expanding street system radiating west from downtown. A suitable material that was inexpensive and could endure the heavy vehicular traffic of the city was not available. The rapid growth of the city combined with limited funding and lack of a competent paving material created a network of streets choked with mud and ravaged with large depressions. One of the earliest paving materials used in the city was limestone extracted from the Mississippi River bluffs. First utilized in St. Louis during 1823, limestone was shaped into uniform blocks and set on a bed of graded sand.[1] Due to the soft nature of the local limestone, heavy vehicular traffic pulverized the stone into a powder. The pulverized stone created a heavy dust during dry weather or a thick mortar-like muck when it rained.

Due to the poor quality and performance of limestone block paving, St. Louis officials decided to apply the new paving technology known as "macadam" in 1832.[2] Created by Scotsman John McAdam, this new technology consisted of a graded road bed of soil with a rise of three inches from its edges to the center, to promote drainage. Crushed limestone consisting of aggregate no larger than two inches was spread upon the graded roadbed. McAdam determined the two inches stipulation was important because the aggregate needed to be smaller in width than the standard carriage wheel. He believed the pressure and friction of traffic would knit the aggregate into a compact surface.[3] Macadamized roads were extremely popular in the United States during the nineteenth century because of their inexpensive production. By 1881, St. Louis had over 300 miles of macadamized roadways.[4] However, the pavement exhibited the same drawback as limestone pavers and needed constant maintenance.

Still faced with the pressures of paving an increasing number of roads with an inexpensive and durable material, St. Louis officials decided to experiment with Nicolson Pavement. Consisting of wood blocks, Nicolson Pavement was implemented by Samuel Nicolson during July of 1848 on Western Avenue in Boston, Massachusetts.[5] Nicolson's system required a graded roadbed covered with one inch thick pine planks coated in boiling tar. Pine blocks roughly measuring ten inches in length by four inches in width were dipped into a cauldron of tar and placed in regular rows, grain end up, on the coated pine planks. A narrow strip of lath was placed between each row to impede shifting of the wood blocks. A final layer of heated gravel and boiling tar was swept onto the pavement and tamped between the crevices. This composition created a smooth, level surface.[6] Nicolson believed his wood block pavement had innumerable advantages over stone paving. The large quantity of tar was used to inhibit moisture and preserve the integrity of the wood block. The movement of traffic would further compact the layer of tar and gravel into the fibers of the wood creating a dense surface preventing the need for repairs. In comparison to the excessive noise created by traffic on stone paving, carriages could proceed along wood block virtually noise free. The abundance of lumber in the United States and wood block pavement's lack of required maintenance made Nicolson's system economical for cities such as St. Louis.

Because of the advantages listed above, St. Louis officials contracted for nearly 60,000 square yards of Nicolson Pavement in 1860.[7] However, within a few years, the disadvantages of Nicolson Pavement became apparent. Its biggest flaw was the tendency of the soft pine material to absorb large amounts of moisture. Lying directly on the ground, the pine planks absorbed moisture and began to rot. The wide joints between the rows, which were filled with pine lath, permitted water to penetrate the pavement, allowing the blocks to swell and heave. These faults coupled with heavy traffic, the blocks were inevitably pounded into shreds. The ruts and depressions became a nuisance and soon, "filled with stagnant water, decaying animals and vegetations."[8] By 1887, only .39 miles of Nicolson Pavement was left in the city. By the following year, all of the original paving was removed and replaced.

Even with these apparent flaws, wood block paving was modified with technological advances and its use was continued across the United States. St. Louis began using harder sweet gum wood, imported from southern Illinois, as pavers. Blocks were placed into a pressurized cylinder and infused with creosote rather than being dipped in tar. The pine plank foundation as replaced with a bed of Portland cement. The treated blocks were set in the cement with the fiber of the wood vertical. The blocks were placed tightly together with joints not to exceed 1/8". After the blocks were placed the surface was smoothed by a steam roller. The final step consisted of filling the joints with sand and covering the pavement with a creosote oil.[9] One of the earliest applications of this modern wood block paver in St. Louis was on Washington Avenue between Compton and Grand Avenues in 1887.[10] By 1893, St. Louis had nearly nine miles of roadway consisting of the modified wood block pavement.[11]

Likely placed between 1890 and 1900, the wood block paver remnants in the alley along 10th street between Olive and Locust Streets, depicts one solution to St. Louis' paving problem. The modified creosote wood paver exemplified the characteristics of a durable and inexpensive material. Not as widely used as stone paving, the modified wood paver continued to be used on St. Louis roadways until the 1930's.